[PATCH] KVM: nSVM: check for EFER.SVME=1 before entering guest

[Paolo Bonzini]

EFER is set for L2 using svm_set_efer, which hardcodes EFER_SVME to 1 and hides
an incorrect value for EFER.SVME in the L1 VMCB.  Perform the check manually
to detect invalid guest state.

Reported-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/svm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 08568ae9f7a1..2125c6ae5951 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3558,6 +3558,9 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
 
 static bool nested_vmcb_checks(struct vmcb *vmcb)
 {
+	if ((vmcb->save.efer & EFER_SVME) == 0)
+		return false;
+
 	if ((vmcb->control.intercept & (1ULL << INTERCEPT_VMRUN)) == 0)
 		return false;
 
-- 
1.8.3.1